The present invention relates to equipment through which subscriber units access a wireless communication system.
Wireless systems, such as PCS and cellular systems, typically include a centralized mobile switching center (MSC) responsible for call routing, user location tracking, billing information, and connectivity with other communication systems. The MSC is connected to base station controllers (BSCs), each of which supports one or more base transceiver stations (BTSs). Each BTS supports one or more cells or cell sectors based on the number and configuration of antennas supported by the BTS. A customer communicates with the wireless system through a wireless unit, such as a radio telephone, when the telephone is within the coverage range of a cell. When a call is placed, a circuit-switched connection is established from the telephone, through the BTS and BSC, to the MSC. The MSC determines the destination and, if the destination is to another telephone within the wireless system, establishes a circuit-switched connection to the destination telephone. If the destination is outside of the wireless system, the MSC routes the call to a service provider for the outside destination.
A key component in any wireless communication system is the antenna forming the edge contact between wireless subscribers and the remaining system. Wireless communication antennas are usually elevated to provide increased coverage range. Often, existing structures such as buildings, towers, utility poles, light poles, and the like provide the necessary elevation. Directional antennas are often used to form focused coverage areas or sectors. Multiple antennas can then be located at one site to provide geographic multiplexing.
When a new antenna location is established, various electrical connections with the antennas must be made. One type of connection carries signals between the antennas and associated transceivers. If transceivers are mounted with the antennas, power cabling and cabling for interconnection with the supporting base station must be provided. This cabling is typically run from the elevated antenna location to pedestals or boxes located on the ground or near the bottom of a pole or tower supporting the antenna. The box provides a convenient location for making power and signal connections. However, the additional work required to mount the box and connect the cabling adds significant cost to the installation of wireless antennas. Such permanent fixtures also make responding to changing communication needs difficult and expensive.
Other problems are associated with the traditional layout of wireless systems. Because all calls are processed by the MSC, it can become a bottleneck limiting the number of users supported. If the MSC fails, the system becomes inoperative. Also, the BSC and BTS architecture is fairly rigid, requiring manual reconfiguration in the MSC when components are added or deleted.
What is needed is a wireless communication system that has greater flexibility and is less expensive to install. In particular, the point at which subscriber units first contact the wireless communication system should be self-supporting, relatively small, and adaptable to a wide variety of wireless applications.
The present invention provides access points for a wireless communication system. The access points require less installation cost and exhibit greater flexibility by not requiring any hard-wired connections to the remainder of the communication system. When pole mounted, these access points do not even require a drop to the base of the pole.
In accordance with the present invention, a wireless access point for communicating with a plurality of wireless subscriber units is provided. The access point includes at least one access antenna for communicating with wireless subscriber units. An access data terminal formats information packets for transmission by and after reception from each access antenna. At least one backhaul antenna interconnects the access point with the remainder of a wireless communication system. A backhaul data terminal formats information packets for transmission by and after reception from each backhaul antenna.
In an embodiment of the present invention, the access point has more than one backhaul antenna. The access point then includes a packet switch routing information between the backhaul antennas and the access antennas.
In another embodiment of the present invention, the access point includes an omnidirectional access antenna.
In yet another embodiment of the present invention, the access point is packaged to permit mounting the entire assembly on a pole.
In further embodiments of the present invention, backhaul transmission may have different characteristics than access transmission. For example, the rate of information transfer for each backhaul antenna may be substantially greater than the rate of information transfer for each access antenna. Also, the transmission frequency for each backhaul antenna may be substantially greater than the transmission frequency for each access antenna.
A method of wireless communication is also provided. For downstream communication, information packets are received through a backhaul antenna and converted to a digital baseband format. The information packets are then converted from the digital baseband format to a broadband format and transmitted from an access antenna. For upstream communication, information packets are received through an access antenna and are converted to a digital baseband format. The information packets are then converted from the digital baseband format to a broadband format and transmitted from a backhaul antenna.
In an embodiment of the present invention, an information packet in a digital baseband format is routed to an access antenna if a subscriber unit to which the information packet is addressed is in communication with the access antenna. Otherwise, the information packet is routed to a backhaul antenna.
A wireless communication system interconnecting a plurality of wireless subscriber units is also provided. The wireless communication system provides a plurality of access points. Each access point includes at least one access antenna for communicating with wireless subscriber units. An access data terminal formats information packets for transmission by and after reception from each access antenna. Each access point also includes at least one backhaul antenna interconnecting the access point with the remainder of the wireless communication system. A backhaul data terminal formats information packets for transmission by and after reception from each backhaul antenna.
In an embodiment of the present invention, each access point is in communication with at least one distribution point. Each distribution point receives an information packet and forwards the information packet to a particular access point in communication with the distribution point if the information packet is destined for a subscriber unit in communication with the particular access point. The information packet is forwarded to another distribution point if the information packet is not destined for a subscriber unit in communication with the particular access point in communication with the distribution point. An access point may be in wireless communication with the distribution point through a backhaul antenna. An access point may also be combined with the distribution point.
The above objects and features as well as other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.